CAVE DRIP WATERS ASSOCIATED WITH SPELEOTHEM FORMATION: INTRA AND INTER-SITE COMPARISON

Dripping water within caves may deposit calcite which accumulates in speleothems, including stalagmites from which increasing numbers of rich paleoenvironmental records are being obtained with precise age-growth models provided by U/Th dates. It is notable that only a subset of the drips within many caves are capable of forming such stalagmites; there is significant spatial variability in hydrogeochemistry even within small zones in caves, whilst the annual laminations detected in many speleothems shows that there is also temporal variability. An understanding of broad patterns of drip water hydrology and chemistry is required for robust interpretation of coeval speleothem paleoenvironmental records from a given cave and also for larger scale, inter-cave correlation of records. In the project presented here 18 calcite-depositing drip water sites from local groups of three in six caves that together span the mid-latitudes of North America were monitored for a minimum of one hydrological year at 15 minute resolution for temperature, electrical conductivity (proxy for total hardness) and drip rate, and monthly bulk water samples were taken for analysis. The poster presents intra and inter-site reviews of drip rate, electrical conductivity, and dD, d¹⁸O, Ca, Mg, Sr data. For most sites, including a series of alpine caves on the Pacific coast, we have found significant seasonality in both dD and d¹⁸O. However, in a cave high in the Canadian Rockies the drip waters proved to be isotopically stationary, as have others in an Austrian alpine cave (Spötl et al 2005). This review aims to elucidate the common elements in karst drip water hydrology and geochemistry that span diverse geological and climatological settings, in broad support of robust paleoenvironmental reconstructions from speleothem calcite.